I. Technical Field
This invention relates to bring up zones for paint baking ovens. More particularly, the invention relates to a method and apparatus for distributing infrared radiation within this bring up zone of a camel-back paint baking oven to increase the temperature of components passing therethrough.
II. Discussion
Paint baking ovens are used throughout the manufacturing industry to bake the paint or coating applied to various articles such as automobile components. Such paint baking ovens often have conveyors or similar devices for bringing the component to be baked into the paint baking oven and then carrying the component through the various sections or zones of the paint baking oven. Generally, the first section or zone of a paint baking oven is known as a bring up zone. In a camel back paint baking oven this bring up zone has traditionally been positioned in the "hump" of such an oven, or, as shown in U.S. Pat. No. 5,155,335 to Habaki et al., in the oblique ramp connecting the oven entrance to the hump portion. While the component being baked is contained in this bring up zone, a heat source is activated which brings the component's body temperature to a desired level. It is well known in the industry that providing a relatively even body temperature over the entire component gives rise to a more consistent baking which, in turn, results in a more desirable finish.
Traditionally, dark radiation panels contained within the hump portion of the oven have been used as the heat source within paint baking oven bring up zones to obtain a relatively even temperature over the component body. The purpose of the radiant heat bring-up zone is to "skin" the paint coating prior to subjecting it to convection heating in a subsequent holding zone--i.e. to remove any stickiness at the outermost layer of the coating. By the time the painted object leaves such a bring-up zone, most of any solvents in the coating have been driven off by radiant heat. Although some success has been achieved through the use of dark radiation panels as a means of increasing the component's body temperature, it is difficult to control the amount of heat generated over specific areas of the component through the use of dark radiation panels. For example, if the component to be paint baked is an automobile component, it has been discovered that dark radiation panels are a less effective way of heating certain parts such as the roof, bonnet, side doors, wheel houses and other heavy parts because they contain inaccessible hidden surfaces.
Another drawback in using dark radiation panels within the bring up zone is the excessive amount of time necessary to increase the temperature of larger components to the desired level.
Until recently, none of the art known to the Applicant utilized infrared lamps within the bring up zone of a camel back oven to quickly increase the component's temperature to a desired level. U.S. Pat. No. 5,155,335 which issued Oct. 13, 1992 to Habaki discloses an infrared heater disposed within the oblique portion of the oven adjacent the elevated horizontal heating chamber. A severe drawback in disposing the infrared heat source within the oblique section of the oven is the likelihood of damage to the infrared heating source from exposure to the excessive heat generated by the elevated horizontal heating chamber. Typically, the convection heating which occurs within the elevated horizontal portion of a camel back oven is carried out at extremely high temperatures, much higher than the infrared lamps are capable of withstanding. Although Habaki discusses the use of a infrared heating source within the oblique portion of a camel back oven, there is no teaching, either express or implied of disposing a heating source such as infrared lamps within the lower horizontal portion of a camel-back oven to thereby function as a bring up zone. Further, none of the art presently known to the Applicant utilize any type of heating source within the lower horizontal portion of a camel-back oven.